A device for diverting flow from a canal drop, small earthen dam or branch to an emergency spillway should a primary diversion fail unexpectedly was required at a small hydroelectric project being developed by the inventors. Several commercial products were available, such as the Obermeir Hydro, Inc. Pneumatically Operated Spillway Gate. This gate consists of a hinged plate held in place by an air bladder. In order to operate, this product includes a control valve, which could fail to operate. In the interest of providing a gate with no controls, a simple, economical alternative was required.